Re: Git Test Coverage Report (Mon. Dec 9)

["René Scharfe" <l.s.r@web.de>]

Am 09.12.19 um 18:44 schrieb Derrick Stolee:
> On 12/9/2019 12:19 PM, Eric Sunshine wrote:
>> On Mon, Dec 9, 2019 at 12:11 PM René Scharfe <l.s.r@web.de> wrote:
>>> Am 09.12.19 um 16:36 schrieb Derrick Stolee:
>>>> René Scharfe  0bb313a5 xdiff: unignore changes in function context
>>>> xdiff/xemit.c
>>>> 0bb313a5 223)        xchp->i1 + xchp->chg1 <= s1 &&
>>>> 0bb313a5 224)        xchp->i2 + xchp->chg2 <= s2)
>>>> 0bb313a5 225) xchp = xchp->next;
>>>
>>> Hmm, line 223 *is* exercised by t4015.85.
>>
>> This, along with Dscho's[1] review of an earlier coverage report,
>> makes one wonder if there is some off-by-one error in the reporting
>> logic, such that it is reporting the wrong lines as not covered.
>
> This is definitely possible. I'll see if I can locate the bug in
> my report-generation code.
>
> However, line 222 is here [1]
>
> 	while (xchp != xch &&
>
> So if this is always false, then the rest of the while condition
> will not be tested, nor will the body (line 225: xchp = xchp->next;).

0bb313a5 also added lines 228 and 229, which are not in the report, so
xchp != xch must be true at least once (it is, in t4015.85).

222)				while (xchp != xch &&
223)				       xchp->i1 + xchp->chg1 <= s1 &&
224)				       xchp->i2 + xchp->chg2 <= s2)
225)					xchp = xchp->next;
226)
227)				/* If so, show it after all. */
228)				if (xchp != xch) {
229)					xch = xchp;

> If it's just an off-by-one error in either direction, then line 224
> still is definitely not covered (which would imply that 225 is not
> covered, either).

Right, hence the patch for t4015 I sent with my first reply.

René